this expression is true only because the exponent is 1
if it were another power you could not do this
other wise the rule is power to power
as to ussually if you break it into mutliple expressions using the rule
the exponent rules ussually just use as default
as you mention probably doesn't relate to much here
but in certain other expressions it would
what you are doing is correct...
it can just get very busy....
on the TI89 use the expand((a+b)^4) and its done
calculus has some better ways to deal with this.
aloha and have nice weekend